**Ruth Britto**

**Associate
Professor in Theoretical Physics**

**Fellow of Trinity
College Dublin**

Dublin 2

Ireland

+353 1 896 3945

**Research**

Scattering amplitudes play a key role in high-energy physics. Not only do they describe the actual scattering taking place in collider experiments--of current importance in the era of the Large Hadron Collider (LHC)--but they also illuminate the formal aspects of quantum field theories, such as divergent behavior or integrability. Amplitudes are thus useful both practically and formally, but their availability is limited by the difficulty of computing them.

As the number of particles in the scattering process
increases, or the perturbative expansion is carried out to higher order, the
traditional technique of Feynman rules fails to be feasibly implementable. This
difficulty has prompted the innovation of new techniques. Notable among these
are *on-shell* techniques, in which the basic building blocks are complete
amplitudes, rather than fundamental interactions. The on-shell framework has
surpassed traditional Feynman diagram expansions, both in delivering new
results and in expressing them in formulas that are not only compact, but also
deeply illuminating. My research develops the on-shell framework to incorporate
all theories and configurations of physical interest, building upon recent
developments in pure mathematics.

**ERC Consolidator Grant Project: Loop
Amplitudes in Quantum Field Theory [***CutLoops***]**

The European Research Council has awarded funding to work on computing multiloop amplitudes from their discontinuities, by examining the relations between generalized cuts and the Hopf algebra of multiple polylogarithms and then exploiting them to produce methods for calculation.

**Innovative Training Network Scattering Amplitudes: from Geometry to Experiment
[SAGEX]**

A network of eight European beneficiary institutions hosting 15 PhD students in the field of scattering amplitudes, in cooperation with international partners from academia and industry. All positions have now been filled.

**COST Action Unraveling
new physics at the LHC through the precision frontier [PARTICLEFACE]**

An interdisciplinary community of European researchers, sharing the aim of shifting the current precision frontier in theoretical high-energy physics to a new level of accuracy, and to create new resources of networking and innovation.

**Publications**

Full list of publications on INSPIRE

Lecture notes: Constructing scattering amplitudes

Review article: Loop amplitudes in gauge theories: modern analytic approaches